1. Field of the Invention
The present invention relates to a method and system for routing a Voice over Internet Protocol (VoIP) call. More particularly, the present invention relates to a method and system for routing a Voice over Internet Protocol (VoIP) call based on a service class of a subscriber, capable of providing a differentiated service according to the subscriber class when a Virtual Private Network (VPN) is used for security of an Internet phone service using VoIP.
2. Description of the Related Art
A technique of transferring voice information using Internet protocol (IP) in a packet switch network used as a data network is called voice over Internet protocol (VoIP). VoIP is not a traditional line-based protocol like a public switched telephone network (PSTN) and transfers voice information in a digital format within discrete packets.
In general, a public network is used in providing a telephony service using VoIP, and therefore security is an important issue.
As one way to provide security, a virtual private network (VPN) is emerging. The VPN is built into an IP network which is provided by a communication company. The VPN is a closed private circuit network that is virtually built within the public network and that is protected by, for example, authentication and encryption technologies.
In the VPN, however, data encryption takes a processing time in encoding/decoding, and a high overhead of packets for encryption and authentication arises.
As such, in the conventional VoIP service, the VPN is used since use of the public network causes a security issue, but the VPN also encounters a difficulty in obtaining a bandwidth.